An open-source, multi-format 1D/2D barcode image processing library implemented in Java, with ports to other languages. [Apache]

Simple Dynamic Strings library for C. [BSD]

The password hash Argon2, winner of PHC. [CC0/Apache2]

Small and lightweight implementations of common algorithms and data structures. [MIT]

A date and time library based on the C++11/14/17 <chrono> header. [MIT] website

The Parsing Expression Grammar Template Library. [MIT]

Cross-platform C++11 header-only library for memory mapped file IO. [MIT]

A Template Engine for Modern C++. [MIT]

Fast, Exact C++ from_chars, 4x to 10x faster than strtod, part of GCC 12, Chromium, Redis, Webkit/Safari. [Apache2/BSL-1.0/MIT]

Fast strong hash functions: SipHash/HighwayHash. [Apache-2.0]

Range-based for loop add-ons inspired by the Python builtins and itertools library. [BSD-2-Clause]

A Pattern-matching library for C++. [BSD]

A lightweight, high performance and scalable C++ library for creating Discord Bots. [Apache2] website

scanf for modern C++. [Apache-2.0] website

A tool that parses archived HTML files from cppreference and generates groff-formatted manual pages for Unix-based systems. [MIT]

A header only library for creating and validating JSON web tokens in C++. [MIT]

Pretty Printer for Modern C++. [MIT]

An open-source SDK for PSP homebrew development. [BSD/GNU GPL3]

Pipelines for expressive code on collections in C++. [MIT]

A C/C++ header file designed to smooth over some platform-specific annoyances. website

Significantly faster input/output for C++20. [MIT]

C++17 std::variant for C++11/14/17. [BSL-1.0]

A library which allows you to compose and modify objects at run time. [MIT]

a C++ library for translating between absolute and civil times using the rules of a time zone. [Apache-2.0]

A cross-platform (C99/C++11) process library. [MIT]

A pretty printing library for C++ containers. [Boost]

A Discord API wrapper library written in C. [MIT] website

almost full-conformance template engine implementation. website

A dependency injection container for C++11 and C++14. [MIT]

A small C library for x86 CPU detection and feature extraction. [BSD]

C++23 procedure hooking library. [BSL-1.0]

Mobile robot simulator. [GPL2]

JSON Web Token library for C++. [MIT]

A typesafe callback system for standard C++. [LGPL] website

A command-line tool that recursively searches a directory to find C/C++ source code matching a search string. [MIT]

a fast and easy lazy evaluation library for C++11/14/17/20. [MIT]

Easy to use and fast C++ CRC library. [BSD-3-Clause]

Fast C/C++ bit population count library. [BSD-2-Clause]

A C++ header-only parser for the PLY file format. Parse .ply happily! [MIT]

C++20 Faker library for generating fake (but realistic) data for testing and development. [MIT]

Rapid fuzzy string matching in C++ using the Levenshtein Distance. [MIT] website

Very fast, high quality, platform-independent hashing algorithm. [BSD-2-Clause]

A simple header file for developers to ban unsafe C/C++ functions from applications.

A semver parser and render in ANSI C. [MIT]

C++20 [Minimal] Static Perfect Hash library. [MIT]

A collection of C/C++ programs that try to get compilers to exploit undefined behavior.

Yet another ONVIF library. [GPL-3.0]

High performance C++11 signals. [PublicDomain]

A safe and fast high-level and low-level character input/output library. [MIT]

A modern C++ library for type-safe environment variable parsing. [Apache-2.0]

The fastest 128-bit and 256-bit non-crypto hash, passes all tests, and under 140 source lines of code. [Apache-2.0]

Fast and standards compliant DNS zone parser. [BSD-3-Clause]

Replacement for std::optional that does not waste memory unnecessarily. [BSL-1.0]

A lightweight library of C functions and structures. [GPL2.1]

A simple C++ header-only template library implementing matching using wildcards. [BSL-1.0]

An implementation of a managed signals and slots system. [Boost] website

A tool to count accesses to member variables in c++ programs. [GPL3]

This Qt lib is based off of the C++ VerbalExpressions library. [MIT]

The Evil License Manager. [GPLv3]

A feature-rich, object-oriented framework for managing variables in C++ / Qt4. [LGPL]

Telegram Bot C++ Library. [MIT]

An alternative to the string library for C which is more functional and does not have buffer overflow overrun problems. Also includes a C++ wrapper. [BSD, GPL2]

A set of c++ core libraries derived from aips++. [LGPL]

Cool cheat sheets and infographics for algorithms, views, containers, randomness, etc.

Fast, Safe C++ Formatting inspired by log4j and Pantheios. [Simplified BSD]

A universal USB library which allows for portable access to USB devices. [LGPL2]

Inter-process communication framework for C++. [GPL2/Proprietary]

A free source code editing component. [MIT]

C++ Signal/Slot Library. [PublicDomain]

A C++ library consisting of high performance string processing routines. [MIT]

A C library of over 100 financial technical analysis indicators. [LGPL]

A barcode scanner library, which allows to scan photos/images/video streams for barcodes and return their value. [LGPL2]